The transition from battlefield adventures to dungeon adventures essentially created RPGs as we known them—the transition from dungeon adventure to wilderness or town adventures introduced the whole idea of “plot” (in the sense of something pre-outlined rather than emergent) to RPGs. – Some More Nice Things About Dungeons by Zak S.

As a kid, I always felt weird when letting my players roam around in the wilderness. I keenly felt the need to lead them by their noses to the adventures I had prepared. Playing the Paizo Adventure Paths in recent years has shown me a solution: big bad is going to happen unless you go right here, right now. I sometimes dislike this sense of urgency because players will usually solve the urgent problems before thinking about their retirement, their castle to build, their temple to found, the guild to run. In a way, it has stifled player plot initiative. Players make no plans if big bad is going to happen real soon.

I did not want to run that kind of game in my Alder King campaign. Instead, I followed this small number of rules for my sandbox wilderness:

there is a conflict between at least three sides, none of them obviously good, and without an obvious big clash coming up in the short term – this eliminates the urgency without removing the option of a showdown at the end of the chapter

the equilibrium situation means that players can easily tip the balance using diplomacy and other means, allowing both referee and players a say in when the chapter should end

travel is one hex a day with random encounters based on nearby lairs and there’s a lair of some sort in practically every hex – the Microlite Campaign idea means that I only need to prepare surrounding hexes while random encounters provide opportunities to learn about foes and potential allies in the area

this makes sure there’s still interesting things in all directions, but it is implied that the players will stay in the area with the three or more side conflict

the limitation given above means that there is in fact an invisible wall around the larger region – moving elsewhere effectively starts a new campaign

making travel difficult also implies that information about remote areas is hard to get by

That still leaves a lot of points raised by Zak unanswered (limited-resource scenario, problem solving, information turning to tactical advantages), but it’s a start.